Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753744Ab0LaQyY (ORCPT ); Fri, 31 Dec 2010 11:54:24 -0500 Received: from mx2.netapp.com ([216.240.18.37]:55749 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752936Ab0LaQyW convert rfc822-to-8bit (ORCPT ); Fri, 31 Dec 2010 11:54:22 -0500 X-IronPort-AV: E=Sophos;i="4.60,255,1291622400"; d="scan'208";a="500639277" Subject: Re: [PATCH v2 00/12] make rpc_pipefs be mountable multiple time From: Trond Myklebust To: Rob Landley Cc: "Kirill A. Shutemov" , Rob Landley , "J. Bruce Fields" , Neil Brown , Pavel Emelyanov , linux-nfs@vger.kernel.org, "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <4D1C5953.6020200@parallels.com> References: <1293628470-28386-1-git-send-email-kas@openvz.org> <20101230085139.GA29697@shutemov.name> <4D1C4C7C.6050606@parallels.com> <20101230094433.GB29697@shutemov.name> <4D1C5953.6020200@parallels.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Organization: NetApp Inc Date: Fri, 31 Dec 2010 11:54:01 -0500 Message-ID: <1293814441.2980.4.camel@heimdal.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 (2.32.1-1.fc14) X-OriginalArrivalTime: 31 Dec 2010 16:54:02.0863 (UTC) FILETIME=[53F71FF0:01CBA90B] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1528 Lines: 40 On Thu, 2010-12-30 at 04:05 -0600, Rob Landley wrote: > On 12/30/2010 03:44 AM, Kirill A. Shutemov wrote: > >>> If no rpcmount mountoption, no rpc_pipefs was found at > >>> '/var/lib/nfs/rpc_pipefs' and we are in init's mount namespace, we use > >>> init_rpc_pipefs. > >> > >> It's the "we are in init's mount namespace" that I was wondering about. > >> > >> So if I naievely chroot, nfs mount stops working the way it did before I > >> chrooted unless I do an extra setup step? > > > > No. It will work as before since you are still in init's mount namespace. > > Creating new mount namespace changes rules. > > Ah, CLONE_NEWNS and then you need /var/lib/nfs/rpc_pipefs. Got it. > > I'm kind of surprised that the kernel cares about a specific path under > /var/lib. (Seems like policy in the kernel somehow.) Can't it just > check the current process's mount list to see if an instance of > rpc_pipefs is mounted in the current namespace the way lxc looks for > cgroups? Or are there potential performance/scalability issues with that? The kernel doesn't give a damn about the /var/lib/nfs/rpc_pipefs bit. That's all for the benefit of the userland utilities. Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/